2.3. Batch Adsorption Experiments

Batch sorption experiments were carried out in 100 mL flasks. HFO-BC or BC (0.01 g) was dispersed into 50 mL aqueous solution with preset concentration of target pollutants. HCl or NaOH solution (1.0 mol/L) was employed to adjust the solution pH, and CaCl₂ and MgCl₂ were served as the background cations, as necessary. The prepared flasks were shaken for 24 h at 180 rpm and 298 K in a thermostatic orbit incubator equipped with the water bath. Based on the preliminary kinetic experiments, it is very sufficient for 24 h to reach sorption equilibrium. As for the kinetic experiment, a certain amount of solution was taken out from the flask and analyzed at preset time intervals. On the basis of mass balance, the sorption capacities and removal of Cd(II) and Cu(II) were acquired.